1. Field of the Invention
The present invention relates an electronic timepiece with a radio communication function such as a radio-controlled timepiece, and relates more particularly to an electronic timepiece with a radio communication function having an antenna positioned within the timepiece relative to one or more other components to facilitate reception of radio waves by the antenna.
2. Description of the Related Art
Radio-controlled timepieces having an antenna to receive a radio signal containing standard time information and adjust the time based on the received time signal are one type of electronic timepiece with a radio communication function for receiving radio frequency (RF) signals from external sources and transmitting RF signals to external devices. Radio-controlled timepieces that have the antenna disposed externally to the case so that the antenna can easily receive RF signals have been proposed (see, for example, Japanese Unexamined Patent Appl. Pub. H11-223684, FIG. 4). This radio-controlled timepiece can receive RF signals with good reception by means of the antenna even if the case member is metal without the metal case interfering with RF signal reception. However, locating the antenna externally to the case detracts from the appearance of the radio-controlled timepiece.
Some radio-controlled timepieces also have solar power generating means, thermal power generating means, or other electrical generating means assembled with the movement of the timepiece, and use the generated output of such generating means to drive the timepiece (see, for example, Japanese Unexamined Patent Appl. Pub. 2003-121569, FIG. 1). However, while the antenna is disposed in the movement and the arrangement of the generating means and antenna are shown in the figures for the radio-controlled timepiece of this patent application, the location of the movement relative to the case is not described. As a result, there could be interference with signal reception by the antenna if, for example, the case is metal, and poor signal reception could result in some situations.
Radio-controlled timepieces having the antenna housed inside the case have also been proposed (see, for example, Japanese Unexamined Patent Appl. Pub. 2002-31690, FIG. 6). The solar cell circuit board in this radio-controlled timepiece is located inside the movement at a position covering the antenna. However, because the solar cell circuit board is usually made from stainless steel or other metal, the circuit board can interfere with signal reception.
A radio-controlled timepiece in which the dial is made from ceramic or other non-metallic material has also been proposed (see, for example, Japanese Unexamined Patent Appl. Pub. 2003-139869, FIG. 1). The back cover or case member of this radio-controlled timepiece, however, must be made from ceramic in order to lower the possibility of interference with signal reception, thus detracting from the appearance of the radio-controlled timepiece. If the back cover or case member is made of metal in order to improve the appearance, signals cannot be received with good reception because the antenna is surrounded by the back cover and case member.